What to do when evidence has validity issues?

I often wonder how different clinicians (and EBM gurus) approach the dilemma of critically appraising  an article only to find that it has a flaw(s). For example, a common flaw is lack of concealed allocation in a randomized controlled trial. Empirical studies show that the effects of experimental interventions are exaggerated by about 21% [ratio of odds ratios (ROR): 0.79, 95% CI: 0.66–0.95] when allocation concealment is unclear or inadequate (JAMA 1995;273:40812). 

bias1

So what should I do if the randomized trial doesn’t adequately conceal the allocation scheme? I could discard the study completely and look for another study. What if there isn’t another study? Should I ignore the data of a perfectly good study otherwise? I could use the study and adjust the findings down by 21% (see above for why) and if the effect of the intervention  still crosses my clinically important threshold then I would implement the therapy. I could use the study as is and assume it wasn’t important because the reviewers and editors didn’t think it was. This is foolish as many of them probably didn’t even recognize the flaw nor would many of them understand the impact.

I don’t have the right answer but wonder what more learned people do. I personally adjust the findings down and determine if I still want to use the information. The problem with this approach is it assumes that in the particular study I am reviewing that the estimate of effect is in fact biased…something I can’t really know.

What do you do?

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